正交直线磨

       此展品也可称为卡尔丹机构椭圆规，如果人推动磨盘，而且扶住手柄的位置不移动，其围绕磨盘走过的轨迹为椭圆。    

ORTHOGONAL STRAIGHT LINE MILL

        This exhibit also called Karton ellipsograph. If you push the handle and keep the position of your hands, the track of your moving will be ellipse.